The present invention relates to an eccentric tensioning device for tensioning a power-transmission means constructed, for example, as a flat belt or toothed belt, in a power-transmission means drive. In particular, the invention here relates to an eccentric tensioning device, which is provided for integration into a power-transmission means drive of an internal combustion engine, which automatically guarantees a required pretensioning of the power-transmission means through an adjustment moment generated on the side of a spring device, and which can be kept in a preassembled mounting state for integration into the power-transmission means drive.
A tensioning device of the type noted above is known, for example, from DE 40 33 777 A1. This conventional tensioning device, also designated as a double eccentric tensioning device, comprises an adjustment eccentric, which makes available a bore arranged eccentrically for receiving an attachment screw. By means of the attachment screw, the tensioning device is mounted on a housing, especially a housing of the internal combustion engine, wherein the adjustment eccentric is supported by means of a base plate on the housing. Placed on this adjustment eccentric is a working or operating eccentric, with there being a slide bearing in an annular gap between a casing surface of the adjustment eccentric and an inner wall of the operating eccentric. On the outside, a surrounds the operating eccentric, whose outer ring functions directly as a running disk, which sits as such in the installed state, i.e., in the operating state, on the power-transmission means of the power-transmission means drive and applies a force to this with a transverse force directed perpendicular to the running direction. For achieving a non-positive contact of the running disk on the power-transmission means, between the base plate and the operating eccentric there is a torsion spring, which forces the operating eccentric and the running disk connected to this operating eccentric continuously into a position tensioning the power-transmission means.